In order to prevent a reversed insertion of a SIM card when the SIM card is inserted into a terminal, a push-push type SIM card is configured such that the reversed insertion is mechanically prevented by a SIM card socket unit of the terminal. In addition, a socket type SIM card is configured such that when the SIM card is inserted into a SIM card socket unit of the terminal in the reversed direction, the reversed insertion can be visually discriminated using the asymmetry of the SIM card.
However, as the size of a SIM card is reduced, the asymmetry portion in a socket type SIM card is also reduced. As a result, it becomes difficult to visually discriminate whether or not the SIM card is reversely inserted into the SIM card socket unit of the terminal.
Also in case of a push-push type SIM card, as the size of the SIM card is reduced, it is expected that a mechanical design that allows the reversed insertion of the SIM card into the SIM card socket unit of the terminal to be detected may become very difficult, and even if such a design is enabled, the reversed insertion of the SIM card may not be confirmed when the reversed insertion of the SIM card is forcibly performed.